Yes PSW will do 25% damage to shielded targets, so this is still a good damage abilitiy to use against shielded targets if you are attacking an AE group (Nanite Cubes in Infected) for example.

It also works if you sit in the middle of the transformers, it can hit all targets. Yipee atleast one damage science ability that has not been nerfed into the ground.

I must admit, I was not aware of the Disruptor proc only working against the hull and not shields (I have had a quick look to confirm, but have come up empty handed), can you provide a link? Even so, people still have bleed through damage which the Disruptor proc will incrase admitably this will only be a 1% increase in damage.

I can't advise on the damage resistance past 0, or even if targets have any resistance. What I can tell you is that my average Photon damage (from Intrepid thread), went from 7500 average mag to 8250 average mag with the switch of Tetryon to Disruptor.